This is a Java servlet filter (as per Servlet API 2.3). This filter lets you proceed If-Modified-Since
header in the request. The If-Modified-Since header field is used with the GET method to make it conditional:
if the requested resource has not been modified since the time specified in this field, a copy of the resource will
not be returned from the server. In this case a status code 304 (not modified) will be returned with empty body.
So you can save bandwidth for static files for example.
How to use it: a) download ifmodflt.jar and save it in WEB-INF/lib b) describe this filter in web.xml.
<filter> <filter-name>IfModFilter</filter-name> <filter-class>com.cj.response.IfModFilter</filter-class> </filter> d) describe a mapping for this filter in web.xml. E.g.:
<filter-mapping> <filter-name>IfModFilter</filter-name> <url-pattern>/html/*</url-pattern> </filter-mapping> and filter will be on for all your files in directory html. Also you can use this filter as a cache solution for your sites. An initial parameter delay describes
a time (in seconds) the actual response will be delayed. This time will be added to the time provided in if-modified-since
header during the status code calculation. E.g.:
<filter> <filter-name>IfModFilter</filter-name> <filter-class>com.cj.response.IfModFilter</filter-class> <init-param> <param-name>delay</param-name> <param-value>600</param-value> </init-param> </filter> So if the requested resource has not been modified since the time specified in if-modified-since plus 600 seconds, the client will get a 304 status code. This parameter lets you provide a delayed response that could be useful in case of heavy traffic for example. See also Last-Modified filter. For downloading: If-Modified-Since package: ifmodflt.jar
See also:
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Also in JSOS:
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